Question

Giải thích dùm mình bài này nha

\(\frac{3}{2.5}\)+\(\frac{3}{5.8}\)+\(\frac{3}{8.11}\)+\(\frac{3}{11.14}\)+\(\frac{3}{14.17}\)

Answer 1

\(\frac{3}{2.5}\)+\(\frac{3}{5.8}\)+\(\frac{3}{8.11}\)+\(\frac{3}{11.14}\)+\(\frac{3}{14.17}\)

=\(\frac{1}{2}\)-\(\frac{1}{5}\)+\(\frac{1}{5}\)-\(\frac{1}{8}\)+......+\(\frac{1}{14}\)-\(\frac{1}{17}\)

=\(\frac{1}{2}\)-\(\frac{1}{17}\)

=\(\frac{15}{34}\)

Answer 2

bn cho mk đi là câu tl sẽ hiện ra

Answer 3

=3(1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17)

=3(1/2-1/17)

=3x15/34

=45/34

mk nha

Answer 4

bn lê hoàng sơn lam tke là sai r

bn bỏ 3 đi đâu r

Answer 5

\(=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{14}-\frac{1}{17}\)\(\frac{1}{17}\)

\(=\frac{1}{2}+\left(\frac{-1}{5}+\frac{1}{5}\right)+\left(\frac{-1}{8}+\frac{1}{8}\right)+...\left(\frac{-1}{14}+\frac{1}{14}\right)-\frac{1}{17}\)

\(=\frac{1}{2}-\frac{1}{17}=\frac{15}{34}\)

Vậy : \(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+\frac{3}{14.17}=\frac{15}{34}\)

Answer 6

15/34 nha bn

Answer 7

cong thua tong qoat ne a/b*(b+a)=1/b-1/(b+a)

Answer 8

la thuc khog phai thua